1. Field of the Inventive Concept
The present inventive concept relates to semiconductor devices and to methods of manufacturing the same. More specifically, the present inventive concept relates to a semiconductor device having a string of gates including (string and ground) selection gates and a group memory gates interposed between the selection gates, and to a method of manufacturing the same.
2. Description of Related Art
A transistor, which is a unit of a semiconductor device, includes a gate electrode formed on a semiconductor substrate and source/drain regions formed in the semiconductor substrate at opposite sides of the gate electrode. A channel extending through the semiconductor substrate connects the source/drain regions across the gate electrode. The source/drain regions are doped with impurities of a conductivity type different from the conductivity type of the impurities of the semiconductor substrate. For example, in a transistor in which the semiconductor substrate contains N-type impurities, the source/drain regions are doped with P-type impurities.
The elements of such transistors are being scaled down to meet the growing demand for high-density semiconductor devices. In this respect, the length of the channel of the gate electrode is becoming smaller. However, a transistor having a small channel length is prone to what are known in the art as short-channel effects. These effects reduce the reliability of the semiconductor device.